Spatially separated exit pupils in a head mounted display

ABSTRACT

Disclosed herein are devices and methods to provide multiple eyeboxes from multiple input pupils. In particular, a projection system can direct light from multiple input pupils to a holographic optical element. The light of each of the input pupils having light beams of different wavelengths. The holographic optical element reflects at least part of the light of the multiple input pupils to form an array of exit pupils.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application Ser.No. 62/240,424 filed Oct. 12, 2015, entitled “Spatially Separated ExitPupils in a Head Mounted Display,” which application is incorporatedherein by reference in its entirety

TECHNICAL FIELD

Embodiments herein generally relate to head worn displays and heads updisplays. In particular, the present disclosure relates to multiple exitpupil head worn display systems.

BACKGROUND

Modern display technology may be implemented to provide head worndisplays (HWD) and heads up displays (HUD). These displays may beimplemented to provide a real world view (e.g., through the display)and/or a virtual view (e.g., images, text, or the like). Such displaycan be implemented in a variety of contexts, for example, defense,transportation, industrial, entertainment, wearable devices, or thelike.

In particular, HWD and/or HUD displays may reflect projected light froma projection surface into a user's eye to provide a virtual image, whichmay be combined with a real world view. Conventionally, HWD and/or HUDsystems have extremely difficult tradeoffs between various design andutility considerations, such as, for example, bulk, form-factor,see-through quality, field of view, etc. For example, a normal eyewearform factor, without bulk, has not been achieved in commercial headmounted displays. In particular, with HWD and/or HUD systems, the fieldof view where information can be overlaid is limited by the opticalsystem eyebox. The eyebox is defined by the tolerances of the opticaldisplay system and limits the placement and movement of the wearer'seye. Conventionally, providing a field of view larger than approximately20 degrees requires bulky optics or complex systems to enlarge theeyebox.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-2 illustrates an example system.

FIG. 3 illustrates an example synthetic eyebox.

FIGS. 4A-4B illustrate a portion of the example system in more detail.

FIG. 5 illustrates a portion of the example system in more detail.

FIGS. 6-9 and 11 illustrate example scanning optical systems.

FIG. 10 illustrates an example optical element.

FIG. 12 illustrates an example optical system.

FIG. 13 illustrates an example logic flow.

FIG. 14 illustrates an example computer readable medium.

FIG. 15 illustrates an example device.

DETAILED DESCRIPTION

Various implementations of the present disclosure are directed to headsup and/or head worn displays and specifically to providing multiple exitpupils for a virtual image to enlarge an eyebox. Said differently, avirtual image can be projected to multiple exit pupils proximate to auser's eye. The multiple exit pupils are spatially separated from eachother to enlarge a viewing area (e.g., eyebox) for the virtual image.

In some examples, an optical system can be provided where light isdirected at a holographic optical element from multiple entrance pupils,where each entrance pupil is spatially separated. Each entrance pupilcan comprise light beams (or bundles of light beams) of differentwavelengths. The light beams of each wavelength, from each entrancepupil, are reflected from the holographic optical element to a differentexit pupil to project a virtual image at the exit pupils. These multipleexit pupils are spatially separated from each other proximate to auser's eye to enlarge a viewing area (e.g., eyebox) for the projectedimage.

With some examples, the multiple entrance pupils can be formed bysplitting light emitted from a light source to direct the light to theholographic optical element from multiple entrance pupils. Saiddifferently, the light can be directed to the holographic opticalelement from multiple different points in space, where each point isspatially separated from the others. In some examples, the entrancepupils are spatially separated in an out-of-plane direction of theholographic optical element. This is described in greater detail below.However, in general, holographic optical elements are selective inangular orientation of incident light. The location of each entrancepupil is selected to provide entrance pupils incident on the holographicoptical element to create multiple exit pupils for each entrance pupil.

For example, two entrance pupils may be provided. The entrance pupilscan be offset from each other in the out-of-plane direction of theholographic optical element. Additionally, light from each entrancepupil can be wavelength-multiplexed in the holographic optical elementto create multiple sets of exit pupils. For example, if the light iswavelength-multiplexed to create two exit pupils, then a total of fourexit pupils can be formed (e.g., two for each entrance pupil). Likewise,multiple sets of exit pupils can be formed by providing three, four, ormore entrance pupils or by wavelength-multiplexing the light from eachentrance pupil to two, three, four, or more exit pupils.

As used herein, an “entrance pupil” and an “exit pupil” are used intheir broadest sense to refer to a spatial position or point where lightenters and exits the system, respectively. Additionally, the presentdisclosure uses a number of example head word displays (HWD) to describevarious implementations. However, this is not to be limiting and thepresent disclosure can be applied to other holographic optical elementreflection type displays, such as, for example, a heads up display.

Reference is now made to the drawings, wherein like reference numeralsare used to refer to like elements throughout. In the followingdescription, for purposes of explanation, numerous specific details areset forth in order to provide a thorough understanding thereof. It maybe evident, however, that the novel embodiments can be practiced withoutthese specific details. In other instances, known structures and devicesare shown in block diagram form in order to facilitate a descriptionthereof. The intention is to provide a thorough description such thatall modifications, equivalents, and alternatives within the scope of theclaims are sufficiently described.

Additionally, reference may be made to variables, such as, “a”, “b”,“c”, which are used to denote components where more than one componentmay be implemented. It is important to note, that there need notnecessarily be multiple components and further, where multiplecomponents are implemented, they need not be identical. Instead, use ofvariables to reference components in the figures is done for convenienceand clarity of presentation.

FIGS. 1-2 illustrate block diagrams of an optical system 1000 to providemultiple sets of exit pupils from multiple input pupils. It is noted,that FIG. 1 is a side view of the system 1000 while FIG. 2 is aperspective view of the system. Furthermore, it is noted that only thechief ray (described in greater detail below) is depicted in thesefigures for clarity of presentation.

In general, the system 1000 is configured to reflect light off aprojection surface 400 to a user's eye 500. Said differently, the system1000 projects a virtual image at exit pupils that are proximate to theuser's eye 500 when a user is wearing and/or using the system 1000. Insome implementations, the projection surface 400 is transparent, forexample, to provide a real world view in conjunction with the projectedvirtual image. In some implementations, the projection surface 400 isopaque. In some implementations, the projection surface is partiallytransparent. It is noted, the projected virtual images can correspond toany information to be conveyed (e.g., text, images, or the like). Use ofthe term “virtual images” is not intended to be limiting to projectionof images or pictures only. Furthermore, in some examples, the system1000 can provide an augmented reality display where portions of the realworld (e.g., either viewed through the display or projected) areaugmented with virtual images. Examples are not limited in this context.

In general, the system 1000 is configured to create multiple sets ofspatially separated exit pupils at the eye 500 of the user of the system1000 (or location where the eye should be or would be if the system 1000were worn or used). These sets of spatially separated exit pupils forman enlarged “synthetic” eyebox (refer to FIG. 3). As such, a largerfield of view or larger projected image may be provided by the system1000. In addition to providing a larger field of view, the enlargedeyebox may account for both person-to-person anthropometric differencesin eye location, and the rotation of a user's eye as the user exploresthe projected image. It is noted, in some examples, the system 1000 canprovide an enlarged field of view to provide a larger projected virtualimage. In some examples, the system 1000 can provide an enlarged fieldof view to provide multiple copies of a projected virtual image suchthat a user can perceive the projected virtual image as the user rotatesthe eye.

The system 1000 may include a projection system 100 to project light toform multiple entrance pupils 200-a, where a is a positive integergreater than 2. For example, light beams corresponding to entrancepupils 200-1 and 200-2 are depicted. Each of the light beamscorresponding to the entrance pupils 200-a are wavelength-multiplexed toform multiple exit pupils 3 b 0-a for each entrance pupil, where b is apositive integer greater than 2. As such, multiple sets of exit pupilsare formed (e.g., one set for each entrance pupil 200-a).

More specifically, the projection system 100 can project light frommultiple entrance pupils 200-a to the projection surface 400. Forexample, the projection system can project light from entrance pupils200-1 and 200-2 to the projection surface 400. Each entrance pupil 200-aincludes multiple light beams, each having a different wavelength. Theprojection surface 400 reflects these wavelength multiplexed light beamsto a first set of exit pupils 3 b 0-a. For example, the projectionsurface 400 can reflect the light beams from the entrance pupil 200-1 tothe set of exit pupils 3 b 0-1 and the light beams from the entrancepupil 200-2 to the set of exit pupils 3 b 0-2. In particular, asdepicted in FIG. 2, the projection surface 400 reflects light fromentrance pupil 200-1 to exit pupils 310-1, 320-1, and 330-1.Additionally, the projection surface 400 reflects light from entrancepupil 200-2 to exit pupils 310-2, 320-2, and 330-2.

In some implementations, each entrance pupil 200-a can correspond to anumber of wavelength multiplexed light beams in a range of wavelengths.More specifically, the projection system 100 can project an input beam(e.g., 200-1, 200-2, or the like) including multiple groups of light,each group having a wavelength similar in perceived color (e.g., λ₁, λ₂,and λ₃) to the projection surface 400. Furthermore, the projectionsystem 100 directs these wavelength-multiplexed light to the projectionsurface 400 from multiple spatially separated points.

In general, the projection surface 400 includes a number of independent,multiplexed gratings (e.g., Bragg gratings, or the like) recorded in it.The projection surface can be referred to as a holographic opticalelement or a volume hologram. The projection surface 400 is wavelengthselective, in that it reflects all (or at least part of) the light froma first wavelength (e.g., λ₁, first group of wavelengths, first range ofwavelengths, or the like) to a first exit pupil location. The projectionsurface 400 reflects all (or at least part of) the light from a secondwavelength (e.g., λ₂, second group of wavelengths, second range ofwavelengths, or the like) to a second exit pupil location. Theprojection surface 400 reflects all (or at least part of) the light froma third wavelength (e.g., λ₃, third group of wavelengths, third range ofwavelengths, or the like) to a third exit pupil location. These exitpupil locations are spatially separated from each other.

For example, FIG. 2 depicts columns of exit pupils 3 b 0-a. Inparticular, a first column of exit pupils, which may correspond to afirst wavelength can include exit pupils 310-1 and 310-2. A secondcolumn of exit pupils, which may correspond to a second wavelength caninclude exit pupils 320-1 and 320-2. A third column of exit pupils,which may correspond to a third wavelength can include exit pupils 330-1and 330-2. More detail regarding the light beams for each respective setof entrance pupils is given with respect to FIGS. 4A-4B and FIG. 5.

It is noted, that only the chief ray of the entrance and exit pupils areshown in FIGS. 1-2 and in FIG. 1, as the exit pupils for each inputpupil are offset in the horizontal direction (or in-plane direction),they are not distinguished from each other. However, they are offset inthe vertical (or out-of-plane direction). Accordingly, the 6 exit pupils310-1, 310-2, 320-1, 320-2, 330-1, and 330-2 are depicted. In thisexample, the three wavelengths at which each input pupil are multiplexedact to spatially separate the exit pupils in the horizontal direction (3across) with 3 multiplexed holograms 401 on the surface 400. The twoentrance pupils 200-1 and 200-2 are used to create two rows of exitpupil. In particular, the leftmost column of the 3×2 exit pupil arraywould correspond to a single wavelength (λ₁) of light from twovertically offset sources. Similarly, for the middle column (λ₂ from twovertically offset sources) and right-most column (λ₃ from two verticallyoffset sources).

Each of the input pupils are angularly separated from each other. It isnoted, that holographic optical elements can be selective in angle andwavelength, however this property depends heavily on the orientation. Inparticular, such holograms can be highly selective in the planeperpendicular to the gratings (e.g., the Bragg direction, or the like).However, such holograms may be much less selective in the orthogonal or“out-of-plane” direction. Accordingly, the multiple input pupils areoffset in the vertical direction of FIGS. 1-2 while the grating of thesurface 400 is setup in the horizontal direction. It is noted, that thegrating (e.g., refer to FIG. 4A-4B) may be configured to wavelengthmultiplex the light either vertically or horizontally. As such, theinput pupils may be either horizontally or vertically separated. It isworthy to note, the chief ray of the exit pupils 310-b corresponding toone entrance pupil 200-1 may not need to be aligned in a “line” asdepicted in FIGS. 1-2. Examples are not limited in this respect.

The projection system 100 projects light onto the projection surface 400from the entrance pupils 200-a. In particular, the projection system 100projects the light onto a portion of the projection surface 400 thatincludes the holographic optical element 401. The holographic opticalelement 401 reflects the incident light to multiple exit pupils 3 b 0-ato (or into) a user's eye 500 so a virtual image can be perceived by theuser.

For example, referring to FIG. 3, an eye 500 and a synthetic eyebox 390are illustrated. The synthetic eyebox 390 includes multiple spatiallyseparated eyeboxes 392-a projected to (or into, or onto) the eye 500 toform the synthetic eyebox 390. For example, eyeboxes 392-1, 392-2, and392-3 are depicted. With some examples, the individual eyeboxes 392-amay correspond to a set of exit pupils 3 b 0-a. For example, the eyebox392-1 may correspond to the exit pupils 310-a, the eyebox 392-2 maycorrespond to the exit pupils 320-a, and the eyebox 392-3 may correspondto the exit pupils 330-a. As another example, the eyebox 392-1 maycorrespond to the exit pupils 3 b 0-1, the eyebox 392-2 may correspondto the exit pupils 3 b 0-2, etc.

It is noted, that the sets of exit pupils are to be created in the outof plane direction of the holographic optical element 401, which isthese figures is vertical. Accordingly, FIG. 1 does not individuallyidentify the exit pupils of each set. In particular, as depicted in FIG.2, the entrance pupils are angularly separated to create multiple setsof exit pupils, in the out of plane direction of the hologram. Morespecifically, the entrance pupil 200-1 may be projected andwavelength-multiplexed to form a first set of exit pupils 310-1, 320-1,and 330-1 while the entrance pupil 200-2 may be projected andwavelength-multiplexed to form a second set of exit pupils 310-2, 320-2,and 330-2.

Examples of the projection system 100 are given in greater detail below.However, in general, the projection system 100 can receive a beam oflight from a laser or may include a laser to generate light beams havingdifferent wavelengths. The projection system 100 can include amicro-electro-mechanical system (MEMS) mirror to scan and/or direct thelight across the projection surface 400 from multiple viewpoints (e.g.,entrance pupils).

With some examples, the projection surface 400 may be a volumeholographic transflector. As noted, the projection surface 400 mayreflect the light projected by the system 100 into the eye 500 toprovide a virtual image in the synthetic eyebox. Additionally, theprojection surface 400 can simultaneously allow light from outside thesystem 1000 (e.g., real world light, etc.) to be transmitted through theprojection surface 400 to provide for a real world view in addition to avirtual view.

In general, the system 1000 may be implemented in any heads up and/orhead worn display. With some examples, the projection surface 400 may beimplemented in a wearable device, such as for example, glasses 401.Although glasses are depicted, the system 1000 can be implemented in ahelmet, visor, windshield, or other type of HUD/HWD display.

Furthermore, additional sets of exit pupils can be created, for example,3 entrance pupils each multiplexed with three wavelengths may form 9exit pupils in a 3×3 array. Examples are not limited in this context.

FIGS. 4A-4B and 5 depict examples of multiple exit pupils formed from asingle input pupil. It is noted, that these figures depict only a singleinput pupil for convenience and clarity of presentation. However, asdiscussed above with respect to FIGS. 1-3, the present disclosure can beimplemented to provide an array of exit pupils formed from multipleinput pupils.

FIGS. 4A-4B show an example of multiple exit pupils corresponding to asingle input pupil. As noted above, the present disclose provides formultiple exit pupils to be formed from a singled input pupil. Forexample, the system 1000 can form the exit pupils 310-1, 320-1, and330-1 from the input pupil 200-1. More specifically, each input pupil iswavelength multiplexed to form multiple spatially separated exit pupils.It is noted, FIGS. 4A-4B depict two (2) exit pupils for convenience andclarity. However, as shown above, more than two (2) (e.g., three (3) aredepicted in FIGS. 1-3) can be formed. It is also noted, holographicoptical elements exhibit “selectivity.” Said differently, theholographic optical element includes features (e.g., reflectiveportions, or the like) for one wavelength of light and angle ofincidence that are independent from features for another sufficientlydifferent wavelength and incidence angle. In this way, sources ofdifferent center wavelength or incidence angle can be used to producemultiple independent exit pupils without crosstalk, thus producing anenlarged effective eyebox.

Further, the multiple exit pupils can be created from wavelengths ofsimilar color in terms of human perception. For example, several exitpupil locations can be created using several different red light sourceswith sufficiently different center wavelengths. The required separationdepends on the spectral selectivity of the surface 400 to preventcrosstalk. The surface 400 can include a recorded holographic opticalelement 401 disposed between protective layers 402 and 403.

Turning more particularly to FIG. 4A, a schematic of an opticalarrangement of two exit pupils 310-1 and 320-1 is depicted. It is noted,that the exit pupils 310-1 and 320-1 are depicted as spatially separatedin a vertical direction. It is noted, the exit pupils 310-1 and 320-1are depicted in the vertical axis (as opposed to the horizontal axisdepicted in FIG. 2) for purposes of convenience and clarity. Examplesare not limited in this context. The exit pupils 310-1 and 320-1 arecreated by multiplexing light beams of different wavelengths originatingfrom a single input pupil. More particularly, light beams (or bundles oflight beams) 211-1 and 221-1 originate from input pupil 200-1. The lightbeam 211-1 has a first wavelength of light while the light beam 221-1has a second wavelength of light, different than the first wavelength.These light beams are reflected by the scanning mirror 105. The scanningmirror 105 scans (or projects) the light beams in angles as projectedlight beams 213-1 and 223-1, respectively. In some examples, thescanning mirror 105 modulates the intensity of the reflected light beamsto correspond to a digital image.

The holographic optical element 401 of the projection surface 400reflects the projected light beams 213-1 and 223-1 into diffracted lightbeams 215-1 and 225-1. In particular, the holographic optical element401 reflects the projected light beams 213-1 and 223-1 towards the twoexit pupil locations 310-1 and 320-1 at the plane of the eye 500. Asdepicted, the eye 500 (having eye pupil 501) has a line of sight 511that is aligned to the center of the exit pupil 310-1. Accordingly, auser (e.g., corresponding to the eye 500, or the like) can perceive animage at the exit pupil 310-1.

However, the system 1000 includes multiple exit pupils, which canprovide a tolerance to eye rotation. Turning more particularly to FIG.4B, a schematic of the optical arrangement of the two exit pupilsdepicted in FIG. 4A is shown with the eye 500 rotated. In particular,the eye pupil 501 and consequently the line of sight 511 of the eye 500has shifted vertically to be aligned with exit pupil 320-1. As such, auser can perceive an image at exit pupil 320-1.

When multiple exit pupils are created, light from a particular positionof the scanning mirror 105 can be projected to a retina of the eye 500.In particular, light from different positions of the scanning mirror,which may correspond to a pixel of an image to be projected, can appearon the retina of the eye 500. As such, irrespective of the eye rotation,a user may perceive the projected image. More particularly, the scanningmirror 105 can reflect wavelength multiplexed light corresponding to animage to be projected from a single input pupil. The holographic opticalelement 401 reflects this wavelength multiplexed light to multiple exitpupils. However, light from these multiple exit pupils can be reflectedto a user's retina such that, irrespective of the user's eye rotation,the user can perceive the projected image.

For example, FIG. 5 depicts the scanning mirror 105 reflecting lightbeams 211-1 and 221-1 from input pupil 200-1. The light beams 211-1 and221-1 can have different wavelengths as described above. The scanningmirror 105 reflects the light beams 211-1 and 221-1 to the projectionsurface 400, which includes a holographic optical element to reflect thelight beams to different exit pupils. The scanning mirror 105 (or othercomponent of the projection system 100) can module the light beams 211-1and 221-1 to correspond to images 581 and 581. By projecting images 581and 582 shifted from each other as depicted, a single apparent image 583can be produced on the retina of the eye 500. More specifically, asingle image can be perceived by a user.

In particular, the pixels 584 and 585 contain the information of thesame image pixel for each exit pupil 310-1 and 320-1. By projectingpixels 584 and 585 on the projection surface with a separation distancesimilar to the separation distance of the exit pupils 310-1 and 320-1,pixels 584 and 585 are reflected by the projection surface 400 asdiffracted light beams 215-1 and 225-1 to exit pupils 310-1 and 320-1,respectively. Additionally, the pixels 584 and 585 merge into one singlepixel 586 on the retina of the eye 500 so the images 581 and 582 areperceived as a single image 583. This is true even when the eye 500 isrotated so the line of sight 511 is shifted.

In some examples, the light beams 211-1 and 221-1 are modulated based onimage processing techniques to laterally shift the projected images foreach of the different wavelength sources. Additional geometriccorrections may be applied, for example, to correct for distortion. Thepresent disclosure may provide systems having additional shifts across2-dimensions. Furthermore, additional pre-processing of the images tocorrect nonlinearities (e.g., distortion, or the like) to improvealignment of the images may be implemented.

FIGS. 6-11, depict example scanning mirror systems, each implementedaccording to the present disclosure. Each of these systems can beimplemented to provide multiple input pupils as described herein. Theseexamples provide that the chief rays incident on the hologram appear,from the perspective of the hologram, to come from different vertical orhorizontal positions on the arm of the eyewear. However, foralternatively biased gratings, the systems can be configured to providechief rays that are offset in the horizontal direction.

Turning more specifically to FIG. 6, a projection system 600 isdepicted. The projection system 600 can be implemented as the projectionsystem 100 of the system 1000. The projection system 600 includesmultiple independent sub-projection systems 610-a, where “a” is apositive integer greater than 2. For example, systems 610-1 and 610-2are depicted. Each of the projection systems 610-1 and 610-2 can includea light source to emit beams of light having different wavelengths. Forexample, light sources 601-1 and 601-2 are depicted. Each light sourceemits light 201 (e.g., 201-1, 201-2, etc.) In some examples, the lightsources 601-1 and 601-2 can include laser light sources, light emittingdiode (LED) light sources, or the like. Additionally, each of theprojection systems 610-1 and 610-2 can include a scanning mirror toreflect light from the respective light source (e.g., light 201-1,201-2, etc.) to the projection surface 400. For example, scanningmirrors 605-1 and 605-2 are depicted. In some examples, the scanningmirrors 605-1 and 605-2 can include micro electromechanical systems(MEMS) including reflectors or mirrors to reflect and module the light(e.g., light 201-1, 201-2, etc.)

The sub-projection systems 610-1 and 610-2 are arranged to each projectmultiple light beams having different wavelengths from spatiallyseparated entrance pupils 200-1 and 200-2, respectively. It is noted,that the sub-projection systems 610-1 and 610-2 are arranged such thatthe entrance pupils 200-1 and 200-2 are spatially separated from eachother in the out-of-plane direction of the projection surface 400. Morespecifically, the entrance pupils 200-1 and 200-2 are spatiallyseparated from each other in the out-of-plane direction of theholographic optical element of the projection surface 400.

Turning more specifically to FIG. 7, a projection system 700 isdepicted. The projection system 700 can be implemented as the projectionsystem 100 of the system 1000. The projection system 700 includes alight source 701, a scanning mirror 705, and an optical element 770. Ingeneral, the light source emits light 201 having multiple light beams ofdifferent wavelengths. The light 201 is received by the scanning mirror705. The scanning mirror 705 projects the light 201 into the opticalelement 770, which directs (e.g., reflects, diffracts, folds, and/or thelike) the light 201 to to the projection surface 400 from multipleentrance pupils. For example, the optical element 770 directs the light201 to the projection surface 400 from entrance pupils 200-1 and 200-2.

Turning more specifically to FIG. 8, an optical element 870 is depicted.The optical element 870 can be implemented as the optical element 770 ofthe projection system 700. The optical element 870 includes prisms 871and 873. The prisms 871 and 873 receive the light (e.g., light 201)projected by the scanning mirror 705 and direct the light to theprojection surface 400 from the perspective of multiple input pupillocations. In particular, the prism 871 directs the light 201 to theprojection surface such that the light 201 appears to originate fromentrance pupil 200-1. Similarly, the prism 873 directs the light 201 tothe projection surface such that the light 201 appears to originate fromentrance pupil 200-2.

Turning more specifically to FIG. 9, an optical element 970 is depicted.The optical element 970 can be implemented as the optical element 770 ofthe projection system 700. In some examples, the optical element 970 maybe implemented as a fold mirror. The optical element 970 receive thelight (e.g., light 201) projected by the scanning mirror 705 and directthe light to the projection surface 400 from the perspective of multipleinput pupil locations. In particular, the optical element folds andredirects the light 201 to the projection surface such that the light201 appears to originate from entrance pupils 200-1 and 200-2.

Turning more specifically to FIG. 10, a perspective view of the opticalelement 970 is depicted. As depicted, the optical element comprisesrefractive surfaces 971 to refract incident light and reflectivesurfaces 973 to reflect incident light. Accordingly, during operation,as depicted in FIG. 9, the optical element 970 can refract and reflectlight 201 through the element 970 to direct the light 201 to theprojection surface 400 from multiple entrance pupils (e.g., 200-1 and200-2).

Turning more specifically to FIG. 11, an optical element 1170 isdepicted. The optical element 1170 can be implemented as the opticalelement 770 of the projection system 700. The optical element 1170includes one or more of a first beam splitter 1171 and a second beamsplitter 1172, a first lens 1173 and a second lens 1174, a wave plate1175, and a mirror 1176.

During operation, light 201 is projected from the scanning mirror 705 tothe beam splitter 1171. The beam splitter 1171 splits the light 201. Inparticular, light is directed from the beam splitter 1171 to theprojection surface from entrance pupil 200-2 and also directed to thefirst lens 1173. In some examples, light 201 is polarized and/ororthogonally polarized based on a desired entrance pupil location. Thefirst lens 1173 reimages the light 201 and transmits the light 201 tothe second beam splitter 1172. The second beam splitter 1172 reflectsthe light to the second lens 1174. The second lens 1174 can collimatethe light 201 and transmit the collimated light 201 to the wave plate1175. The quarter wave plate 1175 rotates the light 201 and transmitsthe rotated light to the mirror 1176. The mirror 1176 reflects therotated light back to the quarter wave plate 1175. The quarter waveplate 1175 again rotates the light 201 and transmits the rotated lightto the second lens 1174. The second lens 1174 focuses the lights andtransmits the light to the second beam splitter 1172. The second beamsplitter 1172 directs the lights to the projection surface 400 from theentrance pupil 200-1.

FIG. 12 illustrates a block diagram of an example projection system1200. The projection system 1200 can be implemented as the projectionsystem 100 of the system 1000. In general, the projection system 1200may be implemented to provide multiple input pupils where each inputpupil is wavelength multiplexed to create an array of exit pupils. Saiddifferently, the projection system 1200 can be implemented to projectlight at a projection surface from multiple input pupils to form a setof exit pupils for each of the multiple input pupils.

The system 1200 may include at least one sub-projection system 1210-a,where “a” is a positive integer. For example, sub-projection system1210-1 and sub-projection system 1210-2 are depicted. Each of thesub-projection systems 1210-a may be provided to provide one or moreinput pupils that are wavelength multiplexed resulting in a set of exitpupils for each input pupil. Each of the sub-projection systems 1210-amay include a light source 1201 (e.g., a laser, an LED, or the like).Additionally, the sub-projection systems 1210-a can include a scanningmirror 1205. The scanning mirror 1205 may be a MEMS based mirrorconfigured to rotate about a number of axes to project light emittedfrom the light source 1201 across a projection surface (e.g., thesurface 400, or the like). Additionally, and particularly where a singlesub-projection system 1210-a is provided, the sub-projection system1210-a can include an optical element 1270. In some examples, theoptical element 1270 as described with respect to FIGS. 7-10. Ingeneral, the optical element 1270 can direct light from the light source1201 and scanning mirror 1205 to a projection surface from multipleentrance pupils.

The system 1200 can also include a controller 1290. In general, thecontroller 1290 may comprise logic, at least a portion of which isimplemented in hardware, to control the sub-projection systems 1210-a.The controller may comprise specially configured logic (e.g., gates,application specific integrated circuits (ASICS), field programmablegate arrays (FPGAS), microcontrollers and associated instructionsexecutable by the microcontroller, or the like. The controller 1290 cansend control signals to the scanning mirror 1205 to cause the scanningmirror 1205 to rotate about a number of axes to project light into theoptical element 1270 and/or onto a projection surface (e.g., the surface400, or the like).

FIG. 13 depicts a logic flow 1300 for projecting a virtual image. Thelogic flow 1300 may begin at block 1310. At block 1310 “project a firstgroup of light beams having multiple wavelengths at a holographicoptical element, the first group of light beams projected from a firstinput pupil,” the scanning mirror (e.g., 105, 605-1, 705, 1205, or thelike) projects light (e.g., light 201) having multiple wavelengths to aprojection surface having a holographic optical element. In particular,the scanning mirror projects the light to the projection surface from asecond entrance pupil location. For example, the scanning mirror 105 canproject the light 201 from the second entrance pupil 200-2, which isspatially separated from the first entrance pupil 200-1. In particular,the first and second entrance pupils 200-1 and 200-2 are spatiallyseparated from each other in the out-of-plane direction of theholographic optical element 401.

Continuing to block 1320 “reflect the first and second group of lightbeams from the holographic optical element, based at least in part onthe wavelength of the light beams, to form multiple sets of exit pupil,”the holographic optical element 401 reflects the light beams from eachentrance pupil to form an array of exit pupils. Said differently, theholographic optical element reflects the light beams from each entrancepupil to form a set of multiple exit pupils for each entrance pupil. Forexample, the holographic optical element 401 can reflect light 201 fromentrance pupil 200-1 to form a set of exit pupils including exit pupils310-1, 320-1, and 330-1. Additionally, the holographic optical element401 can reflect light 201 from entrance pupil 200-2 to form a set ofexit pupils including exit pupils 310-2, 320-2, and 330-2.

FIG. 14 illustrates an embodiment of a storage medium 2000. The storagemedium 2000 may comprise an article of manufacture. In some examples,the storage medium 2000 may include any non-transitory computer readablemedium or machine readable medium, such as an optical, magnetic orsemiconductor storage. The storage medium 2000 may store various typesof computer executable instructions e.g., 2002). For example, thestorage medium 2000 may store various types of computer executableinstructions to implement technique 1300.

Examples of a computer readable or machine readable storage medium mayinclude any tangible media capable of storing electronic data, includingvolatile memory or non-volatile memory, removable or non-removablememory, erasable or non-erasable memory, writeable or re-writeablememory, and so forth. Examples of computer executable instructions mayinclude any suitable type of code, such as source code, compiled code,interpreted code, executable code, static code, dynamic code,object-oriented code, visual code, and the like. The examples are notlimited in this context.

FIG. 15 is a diagram of an exemplary system embodiment and inparticular, depicts a platform 3000, which may include various elements.For instance, this figure depicts that platform (system) 3000 mayinclude a processor/graphics core 3002, a chipset/platform control hub(PCH) 3004, an input/output (I/O) device 3006, a random access memory(RAM) (such as dynamic RAM (DRAM)) 3008, and a read only memory (ROM)3010, display electronics 3020, projector 3022 (e.g., system 1000, orthe like), and various other platform components 3014 (e.g., a fan, across flow blower, a heat sink, DTM system, cooling system, housing,vents, and so forth). System 3000 may also include wirelesscommunications chip 3016 and graphics device 3018. The embodiments,however, are not limited to these elements.

As depicted, I/O device 3006, RAM 3008, and ROM 3010 are coupled toprocessor 3002 by way of chipset 3004. Chipset 3004 may be coupled toprocessor 3002 by a bus 3012. Accordingly, bus 3012 may include multiplelines.

Processor 3002 may be a central processing unit comprising one or moreprocessor cores and may include any number of processors having anynumber of processor cores. The processor 3002 may include any type ofprocessing unit, such as, for example, CPU, multi-processing unit, areduced instruction set computer (RISC), a processor that have apipeline, a complex instruction set computer (CISC), digital signalprocessor (DSP), and so forth. In some embodiments, processor 3002 maybe multiple separate processors located on separate integrated circuitchips. In some embodiments processor 3002 may be a processor havingintegrated graphics, while in other embodiments processor 3002 may be agraphics core or cores.

Some embodiments may be described using the expression “one embodiment”or “an embodiment” along with their derivatives. These terms mean that aparticular feature, structure, or characteristic described in connectionwith the embodiment is included in at least one embodiment. Theappearances of the phrase “in one embodiment” in various places in thespecification are not necessarily all referring to the same embodiment.Further, some embodiments may be described using the expression“coupled” and “connected” along with their derivatives. These terms arenot necessarily intended as synonyms for each other. For example, someembodiments may be described using the terms “connected” and/or“coupled” to indicate that two or more elements are in direct physicalor electrical contact with each other. The term “coupled,” however, mayalso mean that two or more elements are not in direct contact with eachother, but yet still co-operate or interact with each other.Furthermore, aspects or elements from different embodiments may becombined.

It is emphasized that the Abstract of the Disclosure is provided toallow a reader to quickly ascertain the nature of the technicaldisclosure. It is submitted with the understanding that it will not beused to interpret or limit the scope or meaning of the claims. Inaddition, in the foregoing Detailed Description, it can be seen thatvarious features are grouped together in a single embodiment for thepurpose of streamlining the disclosure. This method of disclosure is notto be interpreted as reflecting an intention that the claimedembodiments require more features than are expressly recited in eachclaim. Rather, as the following claims reflect, inventive subject matterlies in less than all features of a single disclosed embodiment. Thusthe following claims are hereby incorporated into the DetailedDescription, with each claim standing on its own as a separateembodiment. In the appended claims, the terms “including” and “in which”are used as the plain-English equivalents of the respective terms“comprising” and “wherein,” respectively. Moreover, the terms “first,”“second,” “third,” and so forth, are used merely as labels, and are notintended to impose numerical requirements on their objects.

What has been described above includes examples of the disclosedarchitecture. It is, of course, not possible to describe everyconceivable combination of components and/or methodologies, but one ofordinary skill in the art may recognize that many further combinationsand permutations are possible. Accordingly, the novel architecture isintended to embrace all such alterations, modifications and variationsthat fall within the spirit and scope of the appended claims. Thedetailed disclosure now turns to providing examples that pertain tofurther embodiments. The examples provided below are not intended to belimiting.

Example 1

An apparatus, comprising: a projection system to project light from aplurality of entrance pupils, each of the plurality of entrance pupilscomprising a plurality of light beams, a wavelength of at least one ofthe plurality of light beams different from a wavelength of at least oneother of the plurality of light beams; and a holographic optical elementin optical communication with the projection system, the holographicoptical element to receive the light from the plurality of entrancepupils and reflect at least a portion of the light to a plurality ofexit pupils.

Example 2

The apparatus of example 1, at least one of the plurality of entrancepupils spatially separated from at least one other of the plurality ofentrance pupils in an out of plane direction of the holographic opticalelement.

Example 3

The apparatus of example 1, wherein each of the plurality of entrancepupils comprises a first light beam having a first wavelength, a secondlight beam having a second wavelength, and a third light beam having athird wavelength, wherein the first wavelength is different from thesecond wavelength and the first and second wavelength is different fromthe third wavelength.

Example 4

The apparatus of example 3, wherein the plurality of exit pupilscomprises a first set of exit pupils corresponding to the first lightbeams having the first wavelength, a second set of exit pupilscorresponding to the second light beams having the second wavelength,and a third set of exit pupils corresponding to the third light beamshaving the third wavelength.

Example 5

The apparatus of example 4, wherein the plurality of exit pupilscomprises a spatially separated exit pupil for each light beam of theplurality of entrance pupils having a different wavelength.

Example 6

The apparatus of any one of examples 1 to 5, the projection systemcomprising: at least one light source to emit the plurality of lightbeams; and at least one micro-mirror device in optical communicationwith the at least one light source, the micro-mirror device to receivethe plurality of light beams and direct the plurality of light beams tothe holographic optical element from the plurality of entrance pupils.

Example 7

The apparatus of example 6, wherein the at least one light sourcecomprises a plurality of light, each of the plurality of light sourcesto emit a one of the plurality of light beams.

Example 8

The apparatus of example 6, the at least one micro-mirror comprises amicro-electromechanical system (MEMS) mirror.

Example 9

The apparatus of example 6, the projection system comprising an opticalelement in optical communication with the mirror, the mirror to projectlight onto the optical element and the optical element to direct theprojected light to the holographic optical element from the plurality ofentrance pupils.

Example 10

The apparatus of example 9, wherein the optical element comprises atleast one of a prism, a fold mirror, a beam splitter, a lens, or a waveplate.

Example 11

A system, comprising: a frame; a projection surface operably coupled tothe frame, the projection surface comprising a holographic opticalelement; and a projection system operably coupled to the frame, theprojection system to project light from a plurality of entrance pupilsto the projection surface, each of the plurality of entrance pupilscomprising a plurality of light beams, a wavelength of at least one ofthe plurality of light beams different from a wavelength of at least oneother of the plurality of light beams, the holographic optical elementto receive the light from the plurality of entrance pupils and reflectat least a portion of the light to a plurality of exit pupils.

Example 12

The system of example 11, wherein the frame is a glasses frame, a helmetframe, or a windshield frame.

Example 13

The system of example 12, wherein the projection surface is a glasseslens, a helmet visor, or a windshield.

Example 14

The system of example 11, at least one of the plurality of entrancepupils spatially separated from at least one other of the plurality ofentrance pupils in an out of plane direction of the holographic opticalelement.

Example 15

The system of example 11, wherein each of the plurality of entrancepupils comprises a first light beam having a first wavelength, a secondlight beam having a second wavelength, and a third light beam having athird wavelength, wherein the first wavelength is different from thesecond wavelength and the first and second wavelengths are differentfrom the third wavelength.

Example 16

The system of example 15, wherein the plurality of exit pupils comprisesa first set of exit pupils corresponding to the first light beams havingthe first wavelength, a second set of exit pupils corresponding to thesecond light beams having the second wavelength, and a third set of exitpupils corresponding to the third light beams having the thirdwavelength.

Example 17

The system of example 16, wherein the plurality of exit pupils comprisesa spatially separated exit pupil for each light beam of the plurality ofentrance pupils having a different wavelength.

Example 18

The system of example 11, the projection system comprising: at least onelight source to emit the plurality of light beams; and at least onemirror in optical communication with the at least one light source, themirror to receive the plurality of light beams and direct the pluralityof light beams to the holographic optical element from the plurality ofentrance pupils.

Example 19

The system of example 18, wherein the at least one light sourcecomprises a plurality of light sources, each of the plurality of lightsources to emit a one of the plurality of light beams.

Example 20

The system of example 18, the at least one mirror comprises amicro-electromechanical system (MEMS) mirror.

Example 21

The system of example 18, the projection system comprising an opticalelement in optical communication with the mirror, the mirror to projectlight onto the optical element and the optical element to direct theprojected light to the holographic optical element from the plurality ofentrance pupils.

Example 22

The system of example 21, wherein the optical element comprises at leastone of a prism, a fold mirror, a beam splitter, a lens, or a wave plate.

Example 23

The system of example 11, comprising a battery electrically coupled tothe projection system.

Example 24

A method comprising: projecting light from a plurality of entrancepupils, each of the plurality of entrance pupils comprising a pluralityof light beams, a wavelength of at least one of the plurality of lightbeams different from a wavelength of at least one other of the pluralityof light beams; and reflecting at a holographic optical element, atleast a portion of the light to a plurality of exit pupils.

Example 25

The method of example 24, at least one of the plurality of entrancepupils spatially separated from at least one other of the plurality ofentrance pupils in an out of plane direction of the holographic opticalelement.

Example 26

The method of example 25, wherein each of the plurality of entrancepupils comprises a first light beam having a first wavelength, a secondlight beam having a second wavelength, and a third light beam having athird wavelength, wherein the first wavelength is different from thesecond wavelength and the first and second wavelengths are differentfrom the third wavelength.

Example 27

The method of example 26, wherein the plurality of exit pupils comprisesa first set of exit pupils corresponding to the first light beams havingthe first wavelength, a second set of exit pupils corresponding to thesecond light beams having the second wavelength, and a third set of exitpupils corresponding to the third light beams having the thirdwavelength.

Example 28

The method of example 27, wherein the plurality of exit pupils comprisesa spatially separated exit pupil for each light beam of the plurality ofentrance pupils having a different wavelength.

Example 29

The method of example 26, comprising: emitting the plurality of lightbeams from one or more light sources; and directing the plurality oflight beams to the holographic optical element from the plurality ofentrance pupils by at least one mirror.

Example 30

The method of example 29, wherein the at least one light sourcecomprises a plurality of light sources, each of the plurality of lightsources to emit a one of the plurality of light beams.

Example 31

The method of example 30, comprising: receiving, at an optical element,light projected by the mirror; and directing, at the optical element,the projected light to the holographic optical element from theplurality of entrance pupils.

Example 32

The method of example 31, the at least one mirror comprises amicro-electromechanical system (MEMS) mirror.

Example 33

The method of example 31, the projection system comprising an opticalelement in optical communication with the mirror, the mirror to projectlight onto the optical element and the optical element to direct theprojected light to the holographic optical element from the plurality ofentrance pupils.

Example 34

The method of example 33, wherein the optical element comprises at leastone of a prism, a fold mirror, a beam splitter, a lens, or a wave plate.

The invention claimed is:
 1. A system, comprising: a frame; a projectionsurface operably coupled to the frame, the projection surface comprisinga holographic optical element; and a projection system operably coupledto the frame, the projection system to project light from a plurality ofentrance pupils to the projection surface, each of the plurality ofentrance pupils comprising a first light beam having a first wavelength,a second light beam having a second wavelength, and a third light beamhaving a third wavelength, wherein the first wavelength is differentfrom the second wavelength and the first and second wavelengths aredifferent from the third wavelength, the holographic optical element toreceive the light from the plurality of entrance pupils and reflect atleast a portion of the light to a plurality of exit pupils, wherein theplurality of exit pupils comprise a first set of exit pupilscorresponding to the first light beam having the first wavelength, asecond set of exit pupils corresponding to the second light beam havingthe second wavelength, and a third set of exit pupils corresponding tothe third light beam having the third wavelength.
 2. The system of claim1, wherein the frame is a glasses frame, a helmet frame, or a windshieldframe.
 3. The system of claim 2, wherein the projection surface is aglasses lens, a helmet visor, or a windshield.
 4. The system of claim 1,at least one of the plurality of entrance pupils spatially separatedfrom at least one other of the plurality of entrance pupils in an out ofplane direction of the holographic optical element.
 5. The system ofclaim 1, wherein the plurality of exit pupils comprises a spatiallyseparated exit pupil for each light beam of the plurality of entrancepupils having a different wavelength.
 6. The system of claim 1, theprojection system comprising: at least one light source to emit thefirst, second, and third light beams; and at least one mirror in opticalcommunication with the at least one light source, the mirror to receivethe first, second, and third light beams and direct the first, second,and third light beams to the holographic optical element from theplurality of entrance pupils.
 7. The system of claim 6, the projectionsystem comprising an optical element in optical communication with themirror, the mirror to project light onto the optical element and theoptical element to direct the projected light to the holographic opticalelement from the plurality of entrance pupils.
 8. The system of claim 7,wherein the optical element comprises at least one of a prism, a foldmirror, a beam splitter, a lens, or a wave plate.
 9. The system of claim1, comprising a battery electrically coupled to the projection system.